Demetallization of heavy petroleum oils



1964 R. B. LONG ETAL 8 DEMETALLIZATION 0F HEAVY PETROLEUM OILS Filed Aug. 22, 1957 HEAVY PETROLEUM on. i

Pl LE 2 WATER IRRADIATION EXTRACTION AIDS 3 4 5 I f WATER WASH a I2 SEPARATION I3 PRODUCT Roberi B. Lor ng Pete J Lucchesi Inventors y a? a. M Aflomey United States Patent 3,154,480 DEMETALLHZATION 0F HEAVY PETROLEUM OILS Robert B. Long, Wanarnassa, and Peter J. Lu'cchesi, Cranford, N..l., assignors to Essa Research and Engineering fiompauy, a corporation of Delaware Filed Aug. 22, 1957, Ser. No. 67 L600 5 Claims. (Cl. 204-154) This invention relates to a process of treating petroleum oils and particularly to a method for reducing the metal content of heavy petroleum oils by irradiating such oils with high energy ionizing radiation, more particularly radiation obtained from an atomic pile, and contacting the irradiated liquid products with a material which selectively removes loosely-bound metals from oils.

Most petroleum crude oils contain metal atoms, a substantial portion of which are in the form of relatively stable compounds which cannot be readily removed except by exceedingly expensive and complicated treatments. It is well known that the presence of metal atoms and metalcontaining compounds in petroleum products is generally undesirable. More particularly, the presence of metals results in undesirable corrosion problems in refinery equipment concomitantly with serious deactivation of catalysts which are essential in petroleum processes. Although numerous methods for removing metals from petroleum oils have been proposed heretofore, there is a continuing need for the development of new and improved methods for purifying petroleum oils.

A novel process has been now found for reducing the metal content of metal-containing petroleum oils, particularly petroleum residua. The present inventors have discovered that the irradiation of metal-containing heavy petroleum oils with high energy ionizing radiation obtained from an atomic pile converts metals in the oil from a relatively stable chemical form to a relatively unstable or loosely-bound chemical form. Further, it has been found that these relatively unstable metals can be readily separated from the irradiated petroleum oil by contacting with a material which selectively removes loosely-bound metals from liquid hydrocarbon compositions. The use of solid adsorbents or aqueous solutions has been found to be particularly effective in this respect. Preferably an aqueous medium is employed. By aqueous medium is meant Water itself or a dilute water solution.

Thus by means of the present invention, relatively stable and unreactive metals in petroleum oils which may be removed only with extreme difficulty, if at all, by conventional methods are converted to a relatively unstable and reactive form which can then be readily removed by contacting with a material which selectively removes loosely-bound metals. The method of the present invention is particularly effective for treating petroleum residua boiling in the range of 900-l500 F. (or higher), which residua are extremely resistant to metal removal by conventional treating techniques. In one embodiment of the invention, the irradiation of a heavy petroleum oil is carried out in the presence of hydrocarbon conversion catalysts. In addition to removing a substantial proportion of the total metal content in the irradiated petroleum oil, the present method also removes a very substantial portion of the radioactive isotopes formed in the pile irradiation by the action of neutrons on naturally-occurring metal atoms.

THE METAL-CONTAINING PETROLEUM OILS The present process is generally applicable to all types of metal-containing petroleum oils. Usually these petroleum oils will contain in the range of about 1 to 1500 parts per million of metal, and usually about 500 to 1000 parts per million of metal.

Metals which can be present in petroleum oils and are susceptible to removal according to the present discovery are generally those which form strongly-bonded, stable, oil soluble metal complexes. Often these have a porphyrin-type structure and gain their stability through coordinate bonding. Such metals have an atomic weight in the range of 30 to 80. Most advantageously petroleum oils which contain oil-soluble compounds of metals selected from the group consisting of iron, nickel, vanadium, chromium, manganese, cobalt, and mixtures of these are subjected, according to this invention, to pile irradiation to the extent that the oils receive a total dosage of radiation energy in the range of 10 -10 electron volts per gram. The present process of treating petroleum oil wherein metals, not susceptible to removal by treatment with solid adsorbents, aqueous media or other conventional metal-removal agents, are converted into a form readily susceptible to removal by conventional processing, provides a method for removing at least 10 percent more metal than was heretofore possible with known techniques.

The metal-containing petroleum oils include not only the virgin stocks obtained from crude distillation units but also include products from other types of hydrocarbon conversion processes such as catalytic cracking, hydroforming, steam cracking and coking. Also, the petroleum oils useful in the present process can be naphthenic, paraffinic and/ or aromatic in nature. The petroleum oils which are employed in the present invention can be classified as follows: (1) petroleum naphthas, (2) petroleum gas oils, and (3) petroleum residua. The petroleum naphthas usually boil within the range of about to 430 F.; the petroleum gas oils boil within the range of about 430 to 1200 F., usually about 650 to 1000 F.; and the petroleum residua usually boil within the range of about 900 to 1500 F. or higher, more usually about l000 to 1300 F. at atmospheric pressure. It will be understood that petroleum oils boiling within the range of about 80 to 1500 F. or higher, at atmospheric pres-1 sure can be employed in the present process.

The present invention is particularly applicable to demetalliza'tion of petroleum residua. These are derived from vacuum pip still bottoms, primary fractionator bottoms from catalytic crackers or cokers, or from deasphalting operations. Specifically, residua are heavy petroleum fractions boiling above 900 F. (indefinite ceiling) containing up to 1500 ppm. of metals which are predominantly V, Ni, Fe. In addition to these metals (usually in the form of porphyrin compounds), residua contain organo-sulfur and organo-nitrogen compounds. The chemical composition of a residuum is mainly high molecular weight aromatics (condensed) and alkyl aromatics. It is that part of the crude that remains after distilling out naphtha, heating oil and heavy gas oil. Its value lies in its extensive use in fuel used by ships and industry and in fluid coking operations. These residua are quite resistant to demetallization by conventional demetallization methods. However, it has been found that the present process is particularly eifective for removing metals from this particular type of petroleum oil.

THE IRRADIATION OF THE METAL-CONTAINING PETROLEUM OILS In the irradiation of the above-described metal-containing petroleum oils, the original metallic compounds are converted to more water soluble or to more strongly adsorbable compounds. The irradiation of the metalcontaining petroleum oils is carried out on either a batch or continuous basis employing the high energy ionizing radiation from an atomic pile (or nuclear reactor). More specifically, for example, a batch operation is carried out simply by exposing the petroleum oil in a container to the ionizing radiation. To carry out a continuous process,

the petroleum oil to be irradiated is pumped through pipes disposed in the atomic pile. The irradiation of the petroleum oil can be carried out in either liquid phase or vapor phase, as desired. During the irradiation, a portion of the petroleum oil may be converted to gaseous products, lower boiling liquid products, higher boiling liquid products and/or solid products. Also, a portion of the metal content in the petroleum oil may be converted to volatile compounds to effect a direct partial purification of the petroleum oil.

Usually the radiation from an atomic pile will consist primarily of neutrons and gamma rays. The slow (thermal) neutron flux existing in these atomic piles usually will be in the range of about to 10 more usually about 10 to 10 neutrons/cmP/sec, and the gamma ray flux will usually be about 10 to 6x10 more usually about 10 to 3 10 roentgens per hour. Slow neutrons are considered to be those neutrons having an energy of less than about 100 electron volts. The present process is most effectively carried out employing fast neutrons, that is, neutrons having an energy more than about 100 electron volts. Usually these fast neutrons will have an energy in the range of about 100 to 2x10 more usually in the range of about 3 10 to 1x10 electron volts. In the normal practice of this invention, from about 10 to 50% (e.g., to 50%) of the neutrons will be in the fast neutron range. The fast neutron flux preferably is in the range of about 10 to 10 and more preferably about 10 to 10 neutrons/crnP/sec. For the above noted fluxes and gamma dosages, total pile energy (from all sources) is absorbed at a rate in the range of 6.8 x10 to 2.1 x 10 e.v./gram/hour.

It will be understood that the irradiation of the petroleum oils in accordance with the present invention can be employed to effect a conversion of the petroleum oil to converted oil products (gases, liquids and/or solids) in addition to converting the stable metals to unstable or loosely-bound metals. The irradiation of the hydrocarhens in accordance with this invention can be carried out employing temperatures in the range of about 50 to 650 F. or higher, usually about 200 to 600 F., and preferably about 300 to 450 F. The present process can be carried out at reduced pressure, atmospheric pressure or elevated pressures (e.g., 1 to 100 atmospheres). However, advantageously, the process will be most conveniently carried out at about atmospheric pressure, at the vapor pressure of the particular petroleum oil, or in the gas phase. The time of irradiation will depend upon the degree of demetallization desired, the particular oil products desired from the irradiation, as well as the radiation dosage rate. Preferably the total radiation dosage from the pile will be in the range of 10 to 10 electron volts per gram of petroleum oil reacted. More preferably the total radiation dosage will be in the range of 10 to 10 e.v./ gram. Thus irradiation times varying from about 1 second or shorter to 10 days or longer, preferably about 5 minutes to 1 day, can be employed. According to the present discovery, the irradiation will be carried out for a time sufficient to effect the conversion of at least about 5 weight percent, usually about 50 weight percent of the petroleum oil to higher boiling liquid products, lower boiling products, gaseous products and/ or solid products.

The present process can be advantageously carried out in the presence of inorganic catalysts which are in a subdivided solid form. Preferably these catalysts are metals or metal oxides. It will be understood that combinations of various metals and combinations of various metal oxides, as Well as combinations of metals and metal oxides, can be employed. Metal removal can also be carried out in the presence of solids that are not catalytic. The subdivided inorganic solids should .be essentially oil insoluble and can be employed in a powder form, that is, wherein the average particle size is generally in the range of about 1 to 1000 microns, or in the form of granules or pellets having an average particle size in the range of about 1000 microns up to 1 inch or more. In other words, subdivided inorganic solids having an average particle size up to about 1 inch or more can be employed in the present invention. The particular particle size which is employed to effect the process will depend generally upon the particular metal or metal oxide employed as well as the specific process conditions employed (e.g., temperature, radiation dosage, feedstock, etc.). The surface area of the solids advantageously will be in the range of 50 to 600 square meters per gram, with a preferred range of about to 300 square meters per gram. Pore sizes vary from 20 to Angstroms with the preferred range from about 30 to 100 Angstroms. Preferably the proportions of solids and oil employed will be about 2:1 to 1:10 volume ratio. More'advantageously the proportions of solids and oil are about 1:1 to 1:2 volume ratio.

Preferably the metals contained in the subdivided solids (including those in the oxide forms) are those which upon neutron bombardment roduce radioisotopes having short half-lives, preferably less than about 24 hours. Specific examples of such metals include aluminum, silicon, magnesium, titanium, and vanadium. It is also preferred that the metals employed be those wherein the fraction of the given metal in the subdivided solids times its capture cross-section be less than about 1 barn (i.e., F X C= 1.0 barns, where F=fraction of the metal in the subdivided solids, and C=capture cross-section of the metal). In this way, metals more susceptible to radioisotope production such as platinum, chromium, nickel, iron, and copper can also be used.

Specific examples of subdivided inorganic solids particularly preferred as contact agents or catalysts in the present invention include:

(1) Silica-alumina.-A useful material of this type is prepared as follows: Alumina is precipitated from aluminum sulfate on either silica gel or previously precipitated silica by the addition of ammonia to the solution. The precipitate is washed, dried (between 200 and 600 F.), calcined for several hours at temperatures up to 1200 F., and then pulverized. The composition of the final product is determined by the proportions of aluminum salt and silica used in preparing the original precipitate. Variations of this technique as practiced by commercial producers of catalyts can also be used.

The compositions of these particular inorganic solids (on a dry .basis) are ordinarily within the following ranges:

Percent Silica 50-97 Alumina 3-50 Only traces of other elements.

Preferred compositions contain from 10 to 40% alumina in the silica-alumina mixture.

The particle size of these materials generally ranges from a few microns to 1000 micron diameter or as pellets or granules from to l-inch diameter. The surface area of commercial catalysts of this type varies from about 50 to 600 square meters per gram, depending on the calcining conditions and other specific preparation techniques. The preferred surface area in operation is from 100 to 300 square meters per gram, with a pore size from 20 to 150 Angstroms.

(2) Platinum on alumina-Such materials are prepared as follows: Alumina (such as prepared in accordance with US. Patent No. 2,636,865) is impregnated with platinum by treating the alumina with aqueous solutions of water-soluble inorganic platinum-containing compounds (e.g., chloroplatinic acid,.ammonium plati num chloride, etc.). For example, an aqueous platinum solution which may be employed is one containing 15 grams of H PtCl .XH O (40% Pt) per liter which will produce an alumina product containing 0.5% Pt. Higher or lower platinum-containing products can be obtained by varying the strength of the'aqueous platinum solution.

The alumina in the platinum-containing aqueous solution is heated to dryness at temperatures of about 100 to 600 F. at atmospheric pressure. The dried product is preferably calcined and is then subjected to a reducing step which may be carried out by treatment with hydrogen at 200 to 1000 F. and at pressures of atmospheric to 1000 p.s.i.g. for about 1 to 24 hours.

These particular inorganic solids contain about 0.001 to 2.0 weight percent of platinum, the remainder being chiefly A1 0 A typical composition (on a dry basis) is as follows:

Percent Pt 0.6 Cl 0.6 A1 0 98.8

The particle size of these materials is usually from a few microns up to 1 inch pellets. The preferred forms are pellets from A -inch to fi-inch diameter and /32 to /2-inch cylinder height.

(3) Alumina-Such materials are prepared as follows:

(1) By dissolving pure aluminum metal in alcohol and reprecipitating, washing, drying, and calcining it after the manner of C. N. Kimberlin, US. Pat. No. 2,636,865.

(2) By neutralizing aluminum sulfate with ammonia, washing, drying and calcining after the manner used to make H-41 type alumina (containing 1l0% silica) which is available commercially from Aluminum Company of America.

(3) By leaching and calcining natural clays to make somewhat impurer aluminas than the above two.

Specific compositions of each of these types of alumina are respectively as follows:

(1) 99.95-l-percent A1 0 with traces of Fe, Na, K, etc.

(2) 5.8% SiO 0.13% Fe O 0.11% Na O, 94% A1 0 (3) These natural aluminas contain up to several percent Fe O Na O, and K 0, the remainder being A1 0 The particle size of these materials is usually from 1 to 1000 microns. If desired, the alumina can be pelleted into granules or pellets up to 1 inch diameter. The surface area per gram varies from about 100 to 300 square meters per gram.

Other examples of subdivided inorganic solids useful as specific contact agents or catalysts in the present invention include boria on alumina, boria on silica-alumina and molybdena on alumina. It will be understood that the above descriptions of the catalysts refer to the material as originally formed, since in the present process the catalysts may be changed in form due to the various chemical, radiochemical and nuclear reactions which may take place.

The use of such catalysts in the present process is advantageous for several reasons: 1) The catalysts aid in the demetallization of the metal-containing petroleum oil. More particularly, certain catalysts such as silica on alumina and platinum on alumina promote the conversion of metals in the petroleum oil to volatile forms which are readily separated from the liquid irradiated products. (They thus effect a direct partial metal removal.) In addition, the subdivided solids adsorb a certain amount of the loosely-bound metal formed in the irradiated petroleum oil and thus also effect a partial metal removal. (2) The catalysts can be selected to promote and control the conversion of the petroleum oil to desired gaseous products, lower boiling liquid products, higher boiling liquid products and/or solid products. (3) The catalysts can be employed to control the amount and distribution of radioactive isotopes in the liquid oil products which are formed during the pile irradiation of naturally-occurring isotopes (contained in the oil feed).

More particularly, when petroleum oils containing metals are bombarded with neutrons, numerous (A|-1) neutron capture reactions take place. The amount of these radioisotopes which are formed and their distribution (based on boiling range) in the liquid products are controlled by the presence of catalyst in the irradiation mixture (with the petroleum oils). The total induced radioactivity left in the irradiated sample varies with the nature of the catalyst used. Another advantage of in corporating the catalysts in the irradiation mixture with the petroleum oils is that substantial proportions of these radioisotopes are selectively absorbed by the catalysts and thus are removed from the liquid products.

CONTACTING OF LIQUID PRODUCTS WITH DEMETALLIZING MATERIALS Upon completion of the above-described irradiation, the liquid products are separated or recovered from the irradiation reaction mixture. Conventional methods for separating liquid products from gaseous and/or solid products can be employed. It will be understood that the total liquid product can be separated into two or more fractions such as can be effected by distillation. For example, in the irradiation of a light gas: oil, a heavy gas oil and a gasoline fraction can be produced by the irradiation. Thus a gasoline fraction and a heavy gas oil fraction can be separated by fractional distillation from the reaction mixture.

The total liquid oil product or fractions thereof can then be contacted in accordance with the present invention with a material which selectively removes looselybound metal from liquid hydrocarbon compositions. This metal removal step can be carried out on either a batch or a continuous basis and can be carried out in either'liquid phase or vapor phase. Usually, however, it will be most convenient to carry out this step in liquid phase. The demetallizing material with which the liquid oil product of the irradiation reaction is contacted can be either a gas, a solid or a liquid. It is preferred, however, to contact the irradiated liquid oil product with either an adsorbent solid material, water, or an aqueous medium. This metal removal step is carried out at temperatures in the range of about 30 to 300 F. When solid adsorbent materials are employed, the preferred temperature range is about 150 to 300 F. When aqueous media or water are employed it is preferred to operate at temperatures of about to 200 F. The use of elevated temperatures in the demetallizing step is advantageous for several reasons. More particularly, the contacting operation is more easily carried out since the viscosity of the liquid oil product is lower at elevated temperatures. In addition, the use of elevated temperatures frequently promotes the removal of a higher percentage of metal from the liquid oil product. Advantageously it will be desirable to carry out the metal removal step at about atmospheric pressure, although it will be understood that lower or higher pressures can be employed if desired.

The aqueous solution with which the liquid oil product from the irradiation is contacted can be water per se, or can be an aqueous solution containing pyridine, or sodium hydroxide, hydrogen chloride, or other inorganic bases or acids. The pH can range from slightly acidic to strongly basic, with a preferred pH slightly on the acid side of neutral, from about 3 to 6. Specific examples of liquid metal removal agents include water, aqueous solutions of sodium hydroxide, potassium hydroxide, ammonium hydroxide, aqueous solutions of nitric or hydrochloric acid and aqueous pyridine solufions. Particularly preferred liquid demetallizing agents are water or weakly acidic hydrochloric acid aqueous solutions.

The proportions of liquid oil product and aqueous demetallizing medium employed will preferably be about 0.1:1 to 10:1 volumes of oil per volume of aqueous medium. More preferably the proportions are about 0.211 to 1:1 volumes of oil product per volume of aqueous medium. The contacting times will be about 0.1

7 to 100 hours, usually about 1 to 10 hours. When employing an aqueous medium it is particularly preferred to contact the irradiated liquid oil product with the aqueous medium in a countercurrent extraction. This can be carried out most effectively, for example, when employing an aqueous solution by introducing the aqueous solution at the top of an extraction tower and the liquid oil product at the bottom of the contacting tower and withdrawing the treated liquid oil product from the top of the contacting tower and the spent aqueous solution from the bottom of the contacting tower. Preferably the two materials, that is, the oil product and the aqueous solution, are thoroughly mixed in the contacting tower.

The liquid oil products from the irradiation can also be contacted with gaseous stripping'and demetallizing agents meters per gram. The preferred surface area is from 100 to 300 square meters per gram, and a pore size of 20 to 150 Angstroms. Specific examples of solid adsorbent materials particularly useful in the demetallizing step of the present invention include silica-alumina cracking catalystsv (spent catalyst or active catalyst), alumina, silica, bauxite, filter clays, carbon black, ion exchange resins, etc. The preferred solid adsorbent materials are spent silica-alumina cracking catalysts and alumina.

No special type of apparatus isrequired for carrying out the novel treating process of the present invention. The features which are believed to be characteristic of the invention both as to its organization and method of operation will be understood more clearly and fully from thefollowing description considered in connection with the accompanying drawing which illustrates schematically one embodiment of the process according to this invention.

Referring to the drawing in detail, it will be seen that a heavy petroleum oil is introduced by line linto av pile irradiation reaction zone 2. The irradiation provided. in zone 2 is obtained from an atomic pileor nuclear reactor. The petroleum material is simply passed through the pile in suitable conduits. It can flow either around or through the core of the reactor, and in some cases the oil itself can serve as the moderator if desired. Suitable conditionsof pressure and temperature are maintained by conventional techniques during the treating process. The total radiation dosage is maintained in the range of 10 to 10 electron volts per gram of feed material.

After irradition treatment the reacted heavy petroleum oil is contacted with water or a dilute aqueous medium. Water is supplied by line 3-from source 4 and well known materials, here called extraction aids, supplied by line 5 from source 6, can be used to facilitate the removal of the loosely-bound metal atoms resulting from the irradiation. These extraction aids include inorganic acids and bases, such assodium hydroxide, hydrochloric acid, potassium hydroxide, nitric acid andammonium hydroxide, pyridine, benzene, and the like. Preferably the pH is slightly. on the acid side of neutral but can be in the range of 2 to 12.

Alternately, the heavy petroleum oils and residua can be subjected to irradiation in the presence of water. released metal atoms concentrate in the Water layer during the bombardment with neutrons. and are thereafter easily removable. In this latter embodiment of the present process, water from source 4 is admitted by line 7 to mix with the heavy oilsupplied by line 1.

Following-the treatment in aqueous medium the product of the radiolysis reaction is passed into zone of where customary water washing techniques are employed. The

The.

amount of water used varies from 0.5 to 10 lbs/lb. of heavy oil. Conventional pressures and temperatures are used. These can be in the range of 1 to 400 p.s.i.g., and 60 to 400 F. This water washing zone can, of course, consist of several stages or can operate counter-currently in a manner well known in the art.

After the water wash, the treated heavy oil is passed by line 9 to separation zone 12, but separation can, of course, occur in zone 8. If a separate separation stage is used, this can include well known separating means such as settling, stripping, distillation, adsorption and absorption. The recovered aqueous medium containing metals separated from the heavy oil is removed by line 13. The treated oil product is removed by line 15 and can be reeyeled by line 17 if desired.

By means of the above-described metal-removal process, the total metal content of the heavy oil product is substantially reduced. Specifically, according to the present invention, up to about 75 to percent of the total metal content can be removed at a feed metal level of 20 to 30 p.p.m. metal. At least 10% of the total metal content of heavy petroleum oils is contained in the separated aqueous layer. Further, up to 60 to 99% of the radioactivity can be removed at a radioactivity level of 100 to 200,000 counts per unit weight and at an experimental counting eiiiciency of 1%.

The invention will be more fully understood by reference to the following examples. It is understood, however, that these examples are given for the purpose of illustration only and are not to be construed as limiting the scope of the present invention in any way. Table I illustrates the novel results of this process.

The atomic pile employed was an air-cooled natural uranium, graphite-moderated research reactor. This pile was operating at a total power of 24 megawatts at the time of these experiments which gave the following flux distribution at the point where the oils were irradiated.

Slow neutron flux (.03 e.v.)

=25 X 10 neutrons/crnP/sec. Fast neutrons flux (1 mev.)

:05 X 10 neutrons/ cm. sec. Gamma intensity: 1.7 X 10 roentgens/ hr.

The core of the reactor was approximately a 20 ft, x 20 ft. x 20 ft. lattic of graphite with horizontal l-inch diameter aluminum-clad uranium rods spaced evenly throughout the reactor extending from the north to south' faces of the core. This core was completely surrounded by 10 ft. of concrete shielding. The sample holes used for irradiation were horizontal 4-inch by 4 inch square holes extending through the 10 ft. concrete shield and into the carbon core for a distance of 10 ft. from the core face. Normal operating temperatures in the experimental hole were from 350 to 400 F. Total pile energy was absorbed by the reactant residua at the rate of about 3.35 l0 e.v./gram/hour.

Example 2 600 cc. of a West Texas residuum having an initial boiling point of 543 F. (50% off at 950 F), was irradiated in the pile in the presence of 600 cc. of spent silica-alumina catalyst (a solid absorbent material). The original silica-alumina catalyst contained 13% by weight of alumina on silica (87 wt. percent) and was in the form of 1 inch diameter cylinders 7 inch high. Prior to its use as a catalyst in a hydrocarbon conversion process, the catalyst had been calcined and and had a surface area of about 500 square meters per gram. The spent silica-alumina catalyst which had been employed in a hydrocarbon conversion process contained about 0.1 wt. percent carbon and 77 grams of absorbed water.

The residuum in contact with the subdivided inorganic solid was irradiated at 300 F. until a radiation dosage of approximately 7 .86 electron volts per gram had been absorbed. The irradiated product was extracted from the solid material and separated by distillation. The fraction boiling about 430 F. was washed alternately in benzene, water, dilute hydrochloric acid and finally pyridine. Metal content of the residuum before and after treatment according to the above novel process was determined in the usual manner employing standard quantitative chemical techniques. Results of the experiment are given in Table II.

TABLE II The above example clearly shows that substantial quantities of nickel and vanadium, resistant to removal by extensive washing techniques alone, can be converted into an unstable chemical form susceptible to easy removal by the same washing treatment by subjecting a petroleum residuum containing such metals to pile irradiation of an intensity and for a duration suflicient that the residuum receives a dose of radiation energy in the range of about 10 -10 electron volts per gram. The subdivided inorganic solid showed high gamma activity after irradiation and separation, proving that a substantial portion of the activated metal had been absorbed from the residuum onto the catalyst.

Example 3 A Bachaquero residuum (875/ 1200 F.) was irradiated and subjected to aqueous treatment in the same manner and under the same conditions as the residuum of Example 2. In this experiment 77 weight percent of the charge Was recovered as a product boiling above 430 F. This unirradiated feed contained 10 p.p.m. of iron, 3 p.p.m. of nickel and 18 ppm. of vanadium. Following irradiation and aqueous washing steps in accordance with the present discovery in the manner described in Example 2, the purified residuum contained 6 ppm. of iron, 2 ppm. of nickel and 1 ppm. of vanadium. Comparison of radiation runs with blank experiments showed the pronounced effect of the present process. The results are truly surprising in the light of the known difiiculty in efiecting removal of vanadium from petroleum oils.

It is to be understood that the above-described arrangements and techniques are but illustrative of the application of the principles of the invention. Although the invention has been described with particular reference to contacting the liquid products of the irradiation process with aqueous medium, it can be utilized with other demetallizing materials which selectively remove looselybound metal from liquid hydrocarbon compositions. For example, the irradiated liquid oil product can be contacted with an absorbent solid material. Alternately a percolation step can be employed. Also, it will be understood that the embodiments of the invention shown and described are but illustrative and that various modifications can be made therein without departing from the scope and spirit of this invention.

What is claimed is:

1. A process for removing metallic impurities from petroleum residua boiling in the range of about 900 to 1500 F., by reducing the porphyrin metallo complex content, which process comprises:

(a) incorporating a subdivided adsorbent hydrocarbon conversion catalyst into said petroleum residua;

(b) subjecting said petroleum residua containing said catalyst, at a temperature within the range of about 200 to 600 F., to high energy ionizing radiation equivalent to a total dosage of radiation energy in the range of 10 to 10 electron volts per gram;

(0) separating said catalyst containing a portion of said metallic impurities adsorbed thereon from said irradiated petroleum residua; and

(d) separating an irradiated petroleum mixture having a reduced porphyrin metallo complex content and an increased content of lower boiling petroleum products.

2. The process of claim 1 wherein said catalyst is a silica-alumina catalyst.

3. The process of claim 1 wherein said radiation dosage is about 10 to 10 electron volts per gram of petroleum residua.

4. The process of claim 3 wherein the volume ratio of said catalyst to said petroleum residua is within the range of about 1:10 to 2:1 and said catalyst has a surface area of about 50 to 600 meters per gram.

5. A process for simultaneously cracking a petroleum residua boiling in the range of 900 to 1500 F. to lower boiling petroleum products and removing metallic impurities from said residua by reducing its porphyrin metallo complex content which process comprises:

(a) incorporating a silica-alumina hydrocarbon conversion catalyst having a surface area of about 50 to 600 meters per gram into said petroleum residua in an amount wherein the volume ratio of said catalyst to said residua is within the range of about 1:1 to 1:2;

(b) subjecting said petroleum residua containing said catalyst to high energy ionizing radiation at a temperature of about 200 to 600 F. for a time suflicient to subject said residua to at least about 10 to 10 electron volts per gram of residua and to eifect at least partial conversion of said residua to petroleum products boiling below about 430 F.;

(c) separating said catalyst containing a portion of said metallic impurities adsorbed thereon from said irradiated residua; and

(d) separating an irradiated petroleum mixture having a reduced porphyrin metallo complex content and an increased content of petroleum products having boiling points lower than about 430 F.

References Cited in the file of this patent UNITED STATES PATENTS 2,743,223 McClinton et a1 Apr. 24, 1956 FOREIGN PATENTS 665,263 Great Britain Jan. 23, 1952 OTHER REFERENCES UCRL3415, pp. 43-44, June 5, 1956. 

1. A PROCESS FOR REMOVING METALLIC IMPURITIES FROM PETROLEUM RESIDUA BOILING IN THE RANGE OF ABOUT 900 TO 1500*F., BY REDUCING THE PORPHYRIN METALLO COMPLEX CONTENT, WHICH PROCESS COMPRISES: (A) INCORPORATING A SUBDIVIDED ADSORBENT HYDROCARBON CONVERSION CATALYST INTO SAID PETROLEUM RESIDUA; (B) SUBJECTING SAID PETROLEUM RESIDUA CONTAINING SAID CATALYST, AT A TEMPERATURE WITHIN THE RANGE OF ABOUT 200 TO 600*F., TO HIGH ENERGY IONIZING RADIATION EQUIVALENT TO A TOTAL DOSAGE OF RADIATION ENERGY IN THE RANGE OF 10**17 TO 10**25 ELECTRON VOLTS PER GRAM; (C) SEPARATING SAID CATALYST CONTAINING A PORTION OF SAID METALLIC IMPURITIES ADSORBED THEREON FROM SAID IRRADIATED PETROLEUM RESIDUA; AND (D) SEPARATING AN IRRADIATED PETROLEUM MIXTURE HAVING A REDUCED PORPHYRIN METALLO COMPLEX CONTENT AND AN INCREASED CONTENT OF LOWER BOILING PETROLEUM PRODUCTS. 